The present invention relates to lever switches, which are used in various electronic apparatuses, for detecting the presence of a recording medium or the operation of a mechanism.
A leaf switch, formed of a combination of a movable contact with fixed contacts, both of the contacts are made of elastic metal thin plate, is well known as a lever switch used for detecting the presence of a recording medium such as a tape or a disc or the operation of various mechanisms.
FIG. 7 through FIG. 9 show a conventional lever switch discussed above. FIG. 7 is a sectional view of the conventional lever switch. Case 31 made from resin is shaped like a box. Case 31 is open in the front thereof and has opening 31A on its upper face. Lever 32 has driving sections 32B and 32C at its lower end and operating section 32D at its upper end. Operating section 32D extends upward from opening 31A.
Movable contact 33 made of elastic metal thin plate and a pair of fixed contacts 34 made of elastic metal thin plate and disposed on both sides of movable contact 33 are rigidly provided respectively on the bottom plate opposite to opening 31A. An upper end of movable contact 33 is inserted between driving sections 32B and 32C. Upper ends of fixed contacts 34 are bowed inside to form contacts 34A facing the intermediate section of movable contact 33. A cover (not shown) covers case 31 that houses movable contact 33 and fixed contacts 34 discussed above. Lever 32 is mounted to case 31 such that lever 32 can rotate on shaft 32A to both sides.
FIG. 8 is a sectional view illustrating a scene where operating section 32D in FIG. 7 is rotated to the right. In this case, since driving section 32C rotates to the left on shaft 32A as a fulcrum, the upper end of movable contact 33 is pushed with driving section 32C and bent leftward. Then the intermediate section of movable contact 33 is brought into contact with contact 34A on the left side.
FIG. 9 is a sectional view illustrating a scene where operating section 32D is further rotated up to a given angle. The upper end of movable contact 33 further moves to the left, and the intermediate section of movable contact 33 pushes contact 34A, so that fixed contact 34 is also bent to the left. As a result, movable contact 33 and fixed contact 34 are kept contacting with each other by a stable contact pressure.
When operating force is removed from operating section 32D, driving section 32C is pushed to the right by the elastic restoring force of movable contact 33 and fixed contact 34. Then lever 32 rotates and operating section 32D is restored to the neutral position as shown in FIG. 7.
When operating section 32D rotates to the left, driving section 32B pushes the upper end of movable contact 33 to the right, so that movable contact 33 is bent to the right and brought into contact with fixed contact 34 on the right side.
In the conventional lever switch discussed above, plate-like movable contact 33 bows to the left or right, so that movable contact 33 is brought into contact with one of fixed contacts 34 on both sides. However, in this mechanism, an appropriate stress to be produced at movable contact 33 requires an adequate length of movable contact 33, so that an entire switch is hard to be downsized.
Further, when lever 32 rotates by the given angle, fixed contact 34 is also bent, whereby the stable contact pressure is obtained between movable contact 33 and fixed contact 34. The contact status thus tends to become unstable when lever 32 rotates halfway.
A lever switch of the present invention comprises the following elements:
(a) a case including a common contact and fixed contacts;
(b) a movable contact including;
(b-1) an intermediate section elastically coming into contact with the common contact;
(b-2) a first arm extending from the intermediate section;
(b-3) a folding-back section formed at an end of the first arm;
(b-4) a second arm extending from the folding-back section; and
(b-5) a contact formed at an end of the second arm and elastically coming into contact with at least one of the inner wall of the case or one of the fixed contacts;
(c) a slider including;
(c-1) an engaging section; and
(c-2) a pushing section coming into contact with to a vicinity of the folding-back section; and
(d) a lever including:
(d-1) an operating section;
(d-2) a shaft which is mounted to the case such that the lever can rotate on the shaft;
(d-3) an contacting section for contacting with the engaging section.
Rotating of the lever brings the contact into contact with one of the fixed contacts, or leaves the contact from one of the fixed contact.